Applicant herein provides conveyor belt splicing fasteners called Bolt Solid Plate Fasteners that include upper and lower plates which are sized to span the ends of a conveyor belt to be spliced together. Each of the plates have a pair of recessed apertures for receiving a pair of bolts extending therethrough to fasten the plates together with the belt ends clamped therebetween. These solid plate fasteners are disclosed in U.S. Pat. Nos. 5,599,131 and 6,345,925, both commonly assigned to the Applicant herein and which are incorporated as if reproduced in their entirety herein.
As disclosed in the '131 patent, it is known to provide a preassembled combination of the lower plates and fastening bolts for ease in the application of the fasteners to the belt ends. In this regard, the '131 patent discloses the use of plastic washers for this purpose with the washers being set at a predetermined position above the lower plates along the shank of the bolts to allow the bolt heads and the shanks extending therefrom to swing in the recessed apertures which is important to allow for proper installation of the fasteners to the belt ends.
The recessed apertures are each formed by a cup that is bent from the material of the plates around their apertures. In the lower plate, the cups are bent upwardly so that the apertures are formed at the upper ends of the walls of the cups. The washers are sized to be larger in diameter than the cup apertures, and specifically the uppermost edge of the cup walls that extend about the cup apertures so as to be in interference therewith thereby keeping the bolts and lower plates in assembled relation. Also, the lower cups and bolt heads are provided with cooperating anti-rotation structure in the form of diametrically opposed notches in the cup so that cup wall is formed by a pair of arcuate wall portions. This leaves radially inwardly extending tabs of the lower plate between the arcuate wall portions and below the cup wall notches for being received in corresponding notches formed in the bolt head.
In the '131 patent, the washers are disclosed as being of an extrudable plastic material so that when the bolt plate fastener is installed on the belt ends with the belt ends clamped between the upper and lower plates, the washers will be forced down along the shank of their respective bolts and into engagement with the lower cups to be deformed into the spaces between the bolts and the surfaces of the cup arcuate wall portions as well as around the outer, upwardly facing surfaces of the cup wall portions since the washers each have a larger outer diameter than that of the cup wall uppermost edge extending about the aperture. Thus, there can generally be washer material that remains between the cups of the lower plate and corresponding cups of the upper plate when the fastener plates are clamped together on the belt ends.
Where the belts are relatively thin, e.g. 3/16 inch in thickness between the belt upper and lower surfaces, installers generally like to be able to believe that the cups of the recessed apertures of the upper plates will engage the cups of the lower plates by forcing the pliable belt material out of the way when the plates are clamped onto the belt ends. In this manner, the installed plate fasteners will not unduly increase the profile of the relatively thin belts. However, with the material of the plastic washers engaged against the lower cups, and particularly the outer surface thereof, the washers can present a barrier to the low profile application of the bolt plate fasteners to belt ends of thin conveyor belts.